The present invention relates to the field of powering data terminal equipment and more particularly to a dual port pass through midspan having a pass through data connection, wherein a pair of powered devices are connected via the dual port pass through midspan, without requiring hub equipment.
Ethernet communication, also known as IEEE 802.3 data communication, is typically implemented over a structured cable having 4 twisted wire pairs. Power of Ethernet (PoE), as described in IEEE 802.3af—2003 and IEEE 802.3.at—2009, as published by the Institute of Electrical and Electronics Engineers, New York, the entire contents of each document is incorporated herein by reference, is superimposed over the data utilizing phantom powering. In particular, the existing data transformers of Ethernet are center-tapped, with center taps connected to opposing polarity leads of a power sourcing equipment (PSE) and thus the DC current through the two halves of the transformer are of equal magnitude and opposite direction leaving no net flux in the transformer core.
The PSE may be an endpoint PSE, i.e. a PSE associated with the hub equipment, or a midspan PSE, i.e. a PSE arranged between the hub equipment and the PD. The term midspan, as used herein, is meant to include an unit comprising one or more PSE arranged to be installed between DTEs, irrespective as to whether one of the DTEs is a hub or switch equipment, or any other DTE.
Ethernet communication for speeds less than 1000 megabits per second (Mbps) is typically supplied over 2 twisted wire pairs, one of the pairs being used as a transmit pair from the hub equipment to the data terminal equipment (DTE), which when powered by PoE is also known as a powered device (PD), and a second of the pairs being used as a transmit pair from the data terminal equipment to the hub equipment. The other two pairs were typically not used, and are known as spare pairs. In such an embodiment either spare powering, or data pair powering, may be implemented. Ethernet communication for speed of 1000 Mbps and above is typically supply over all 4 twisted wire pairs, with bidirectional communication performed over each of the 4 twisted wire pairs. Powering is typically performed over two twisted wire pairs, analogously to the powering for low speed Ethernet. In certain embodiments, power is provided over all 4 twisted wire pairs.
PoE has enabled remote equipment installation to rapidly expand, since local mains power is not required. PoE is typically delivered at a voltage or around—48 volts, which is typically considered low voltage from a safety perspective. Thus, power and data may be supplied over a single cable, which typically does not require a licensed installer. PoE thus provides ease of installation for remote surveillance cameras, and wireless access points, without limitation.
PoE is further taught in various patents, including U.S. Pat. No. 6,473,608 issued Oct. 29, 2002 to Lehr et al., the entire contents of which is incorporated herein by reference.
FIG. 1 illustrates a high level block diagram of a prior art midspan powering arrangement 10 arranged to provide power and data for a remote surveillance camera 20 and a wireless local area network (LAN) access point 30. Power for both remote surveillance camera 20 and wireless LAN access point 30 is provided by dual port midspan 40, and data communication is provided by hub equipment 50. There is no requirement that hub equipment 50 be provided with a direct wired network connection, although this is typically done, since communication with hub equipment 50 may be provided via wireless LAN access point 30, which may act as a router or switch, without limitation. Such an arrangement provides data communication to a network, remote from the installation, via wireless LAN access point 30, but is quite cumbersome as it requires 4 distinct pieces of equipment and 4 data cables. AC mains power is supplied to each of dual port midspan 40 and hub equipment 50. While AC mains power is illustrated herein, this is not meant to be limiting in any way, and a DC mains may be utilized without exceeding the scope.
It is to be understood that in the event that remote surveillance camera 20 is replace with an additional wireless LAN access point 30, midspan powered arrangement 10 may function as a wireless repeater.